Joint fluid Gram stain

Definition:

Joint fluid Gram stain is a laboratory test to identify bacteria in a sample of joint fluid using a special series of stains (colors). The Gram stain method is one of the most commonly used methods to rapidly diagnose bacterial infections.

The fluid sample is sent to a lab where a small drop is placed in a very thin layer onto a microscope slide. This is called a smear. Several different colored stains are applied to the sample. The laboratory personnel will look at the stained smear under a microscope to see if bacteria are present. The color, size, and shape of the cells help identify the bacteria.

Review Date: 11/13/2011
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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